1. Field of the Invention
This invention relates to a tarp assembly for covering the load bed of a truck. More particularly, this invention relates to a tarp assembly for extending a tarp over a container positioned on a roll-off bed of a container truck during transport and for retracting the tarp to permit the container to be rolled off the bed of the truck and an empty container loaded thereon.
2. Description of the Background Art
Presently there exist many types of tarp assemblies designed to position a tarp over the load bed of a truck to prevent materials being blown or jostled from the load bed onto the highway. Most jurisdictions require such tarp systems for the safety of passenger vehicles from flying materials.
Tarp assemblies typically comprise a tarp that is wound onto a tarp roll-up bar. The tarp roll-up bar is journalled to the front of the load bed of the truck. The end of the tarp is connected to a rear cross bar connected between a pair of arms that pivotably extend from the sides of the truck bed. Rearward extension of the arms unroll the tarp from the roll-up bar thereby extending it over the opened top of the load bed. Materials are therefore prevented from being blown or jostled from the load bed onto the highway.
Tarp assemblies are usually manually operated, electrically operated or hydraulically operated. Manually operated tarp assemblies often include a pair of spring mechanisms that are operatively connected to the pivoting ends of the arms to tension the arms rearwardly to unroll the tarp from the roll-up bar over the load bed. A manual crank is connected to the tarp roll-up bar such that upon cranking, the tarp is wound back onto the roll-up bar to a retracted position clear of the load bed of the truck. The roll-up bar is then locked to prevent unrolling of the tarp from the roll-up bar due to the tension of the spring assemblies. Electrically operated tarp assemblies have a similar construction with an electric motor operatively connected to the roll-up bar in lieu of the manual crank.
Hydraulically operated tarp assemblies commonly employ a spring-loaded roll-up bar that exerts tension on the tarp to roll-up the tarp onto the roll-up bar. In lieu of spring assemblies, hydraulic assemblies are operatively connected to the pivoting ends of the arms. When actuated rearwardly, the hydraulic assemblies extend the arms rearwardly to unroll the tarp from the roll-up bar over the load bed. When the hydraulic assemblies are actuated forwardly, the arms are retracted over the load bed of the truck as the spring-loaded roll-up bar rolls up the tarp. See for example, U.S. Pat. No. 5,058,956.
The majority of the tarp assemblies are installed on dump trucks with the roll-up bar being mounted to the cab shield of the load bed and the ends of the paired arms being connected to the lower sides of the load bed. In this manner, the load bed together with the tarp assembly may be pivoted upwardly to dump the material from the load bed.
It is also known to utilize hydraulically operated tarp assemblies in connection with container trucks designed to haul 20 or 40 cubic yard containers on a roll-off bed of the truck. In these tarp assemblies, the roll-up bar is mounted to a gantry framework mounted to the truck frame in front of the tilt frame of the roll-off bed. The ends of the paired arms and the hydraulic assemblies are mounted to the sides of the truck frame away from the sides of the tilt frame. In this manner, the paired arms of the tarp assembly may be extended rearwardly to pull the tarp to cover the opened top of a container positioned on the roll-off bed of the truck thereby preventing material in the container from blowing onto the highway during transport. After transport, the paired arms may be retracted fully forward and the tilt frame tilted upwardly to roll-off the container filled with the material and to load an empty container onto the roll-off bed.
It is noted that 40 cubic yard and 20 cubic yard containers are commonly used throughout the industry. The height of the 40 cubic yard containers is significantly higher than 20 cubic yard containers. Hence, the gantry framework is usually positioned substantially level with the top of a conventional 20 cubic yard container and is made to be upwardly adjustable by means of a hydraulic cylinder to be substantially level with the top of a conventional 40 cubic yard container. The adjustability of the gantry framework is required in order for the tarp assembly to fully cover 20 and 40 cubic yard containers without the wind catching under the tarp during transport and blowing the materials from the container onto the highway. Unfortunately, the upward adjustability of the gantry framework substantially increases the complexity and resulting cost of manufacture and installation of the tarp assembly.
The above-described hydraulically operated tarp assembly for container trucks has not been widely accepted in the trade due to the expense of utilizing the hydraulic cylinders for the gantry framework and the hydraulic cylinders in the hydraulic assemblies. Hence, there presently exists a need in the industry for more affordable tarp assemblies for container trucks that may be easily retrofitted to existing container trucks.
Therefore, it is an object of this invention to provide a tarp assembly that overcomes the aforementioned inadequacies of the prior art tarp assemblies and provides an improvement that is a significant contribution to the advancement of the tarp assembly art.
Another object of this invention is to provide a tarp assembly for a container truck that is operable without the need for hydraulic cylinders and associated controls.
Another object of this invention is to provide a tarp assembly for a container truck that is less complex and therefore more affordable.
Another object of this invention is to provide a tarp assembly for a container truck that is easily retrofitted to existing container trucks without special expertise.
Another object of this invention is to provide a tarp assembly for a container truck that includes a fixed-height gantry framework that still allows the tarp to cover conventional 20 and 40 cubic yard containers.
Another object of this invention is to provide a tarp assembly having a fixed-height gantry framework and a pivotable hold-down bar that forces the front area of the tarp downwardly over the front edge of a smaller sized (e.g., 20 cubic yards) container thereby preventing wind from catching under the front of the tarp and blowing it upwardly away from the rim of the container.
The foregoing has outlined some of the more pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results can be obtained by applying the disclosed invention in a different manner or modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description of the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.